ImguiWgpuBackend._update_texture: want_create upload uses update_rect instead of full texture size

[ro0o0o0okie]

imgui_backend.py

_update_texture uses tex.update_rect.w / h as the write extent for want_create, but update_rect only covers modified regions, not the whole texture. The GPU texture ends up partially uninitialized — CJK fonts show missing glyphs with demo window enabled, and all glyphs disappear when tex_glyph_padding is left at default (1).

The bug:

# imgui_backend.py L157-165
if tex.status == imgui.ImTextureStatus.want_create:
    upload_x = 0
    upload_y = 0
else:
    upload_x = tex.update_rect.x
    upload_y = tex.update_rect.y

upload_w = tex.update_rect.w   # should be tex.width for want_create
upload_h = tex.update_rect.h   # should be tex.height

C++ reference (imgui_impl_wgpu.cpp):

const int upload_w = (tex->Status == ImTextureStatus_WantCreate) ? tex->Width  : tex->UpdateRect.w;
const int upload_h = (tex->Status == ImTextureStatus_WantCreate) ? tex->Height : tex->UpdateRect.h;

The GPU texture is created at tex.width × tex.height , so the upload should match that. Fix is straightforward: use tex.width / tex.height for want_create.

Proposed fix

  -        upload_w = tex.update_rect.w
  -        upload_h = tex.update_rect.h
  +        if tex.status == imgui.ImTextureStatus.want_create:
  +            upload_w = tex.width
  +            upload_h = tex.height
  +        else:
  +            upload_w = tex.update_rect.w
  +            upload_h = tex.update_rect.h

[Vipitis]

Hey, thanks for bringing this up.

Could you provide a small example where the issue happens?

the change looks good to me, would you be able to open a PR?

[ro0o0o0okie]

Thanks for the reply!

A self-contained example (in my case) needs CJK font + gui rendereing window setup, so it's not exactly one-liner.

Since the change is small (3 lines), well-scoped, and directly mirrors the upstream fix,
I'd prefer not to open a PR this time. Feel free to apply it at your convenience.